The PdAu random alloy nanoparticle catalyst shows excellent catalytic activity for heterogeneous molecular formations, whereas monometallic Pd or Au catalysts were ineffective. The Pd/Au ratio in the alloy had a significant impact on its catalytic performance, and the catalyst with a low Pd concentration exhibited excellent activity. The concerted catalysis of Pd and Au adjacent on the alloy surface is responsible for the specific catalytic performance.